(1) Field of the Invention
The present invention relates to a slide member formed in a cylindrical shape for a shock absorber provided between a vehicle body and a wheel of a vehicle for supporting a piston rod reciprocally sliding in an axial direction in a shock absorber.
(2) Description of Related Art
In order to enhance ride quality such as steering stability and running stability, a shock absorber is provided between each wheel and a vehicle body in, e.g., a vehicle as typified by automobiles. A common multi-cylinder shock absorber is used to relieve and damp a rocking phenomenon (periodic vibration) of expansion and contraction due to spring characteristics so that, in the contraction action, damping force (pressure loss) is generated by channel resistance when the same amount of oil as the volume of a piston rod entering a cylinder passes through a contraction-side valve while, in the extension action, the damping force is generated by the channel resistance when the same amount of oil as the volume of the piston rod coming out of the cylinder passes through an extension-side valve. For such a shock absorber, a slide member configured to reciprocally slide on the piston rod coupled to a vehicle body is used, and a surface roughness of a slide surface of the slide member is reduced as much as possible to reduce friction force generated between the piston rod and the slide surface of the slide member (see JP-A-2003-247546, for example).
Further, as another conventional shock absorber, there is proposed a shock absorber in which convex portions each having a point peak or a linear peak are formed on a slide surface of a slide member to inhibit formation of an oil film on the slide surface and thus increase dynamical friction force generated between a piston rod and the slide surface of the slide member (see JP-B2-5354134).